Well known forms of electronic packages are the land grid array (LGS) and ball grid array (BGA) package in which an electronic circuit, typically an integrated circuit, is contained within a thin rectangular housing having an array of electrical contacts on a surface of the package. Such a package is typically mounted to a corresponding array of contact areas of a printed circuit board. Since LGA or the BGA package is soldered directly to a circuit board, the package is not removable from the board without unsoldering. Sockets are known for removably mounting electronic circuit packages onto printed circuit boards; however, sockets for LGA or BGA packages have not heretofore been successfully implemented. Test sockets are known for testing such packages but such test sockets are generally complex and relatively large and cumbersome and are impractical for use in usual circuit board environments.
In brief, a socket for an LGA or BGA package is provided which is of relatively simple construction and which provides reliable and efficient interconnection of an LGA or BGA package and a printed circuit board. The socket comprises a contact assembly having an array of resilient conductive columns having respective contact ends, the columns being mounted on a thin insulative sheet. The contact assembly is supported on a frame of insulating material and which has alignment posts for alignment of the contact assembly to the frame and for alignment of the frame and mounted contact assembly to an associated circuit board. The frame also includes elements for soldering or bonding the socket to a circuit board.
The socket is soldered or otherwise bonded onto a printed circuit board which has an array of contact areas corresponding to the array of resilient contacts of the socket. An LGA or BGA package is placed onto the socket frame and the package is maintained in alignment on the frame such that the package contacts engage the respective contacts of the contact assembly of the socket. The package is retained in the socket by a retention mechanism. The socket can include elements for preventing overstress of the resilient contacts.
The conductive columns can have the contact ends which engage the circuit board coated with a conductive polymer or other material which bonds to the contact areas of the circuit board. The other contact ends of the conductive columns which engage the package contacts do not bond to those package contacts so that the package remains removable from the socket.